Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/Documentation/bpf/maps.rst b/Documentation/bpf/maps.rst
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+
+=========
+eBPF maps
+=========
+
+'maps' is a generic storage of different types for sharing data between kernel
+and userspace.
+
+The maps are accessed from user space via BPF syscall, which has commands:
+
+- create a map with given type and attributes
+  ``map_fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size)``
+  using attr->map_type, attr->key_size, attr->value_size, attr->max_entries
+  returns process-local file descriptor or negative error
+
+- lookup key in a given map
+  ``err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size)``
+  using attr->map_fd, attr->key, attr->value
+  returns zero and stores found elem into value or negative error
+
+- create or update key/value pair in a given map
+  ``err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)``
+  using attr->map_fd, attr->key, attr->value
+  returns zero or negative error
+
+- find and delete element by key in a given map
+  ``err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size)``
+  using attr->map_fd, attr->key
+
+- to delete map: close(fd)
+  Exiting process will delete maps automatically
+
+userspace programs use this syscall to create/access maps that eBPF programs
+are concurrently updating.
+
+maps can have different types: hash, array, bloom filter, radix-tree, etc.
+
+The map is defined by:
+
+  - type
+  - max number of elements
+  - key size in bytes
+  - value size in bytes
+
+Map Types
+=========
+
+.. toctree::
+   :maxdepth: 1
+   :glob:
+
+   map_*
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